class Person {
}

class Student extends Person {
    study() {

    };
}

function doSomething(p: Person) {
    (p as Student).study();
}


const mess: string = "lbwnb";
const num: number = (mess as unknown) as number;

function printMessLength(mess: string) {
    console.log(mess!.length);
}

printMessLength(mess);


let message: string | null = '??';
const constant = message ?? "other";
// const constant = message ? message : "other";


export {}
